Hypericum perforatum

St John's wort

Family: Clusiaceae

Origin: Eurasia, North Africa

St John's wort growing wild in a field.
St John's wort is an upright perennial herb that grows up to 1.2m tall and can be toxic to livestock.

Regional Pest Management Plan (RPMP) status

  • Not a legally declared pest

View more about the RPMP statuses

General description

Erect perennial herb < 1.2 m tall. Rhizomes are slender and creeping. Stems are woody near the base, many-branched and have 2 longitudinal ridges. Leaves are opposite, stalkless and have translucent and occasionally black dots. Flowers are yellow with small black dots on the edges and are borne in terminal clusters in December – March. Fruit is a sticky capsule containing many pitted seeds and is green when young, ripening to brown.

What you need to know

Although St John’s wort is not a legally declared pest plant, it may still be invasive in some situations. Consider lower risk alternatives for your garden, such as native plants.


Open areas, forest, riparian margins, grasslands, pasture, plantations, wasteland, roadsides.


Seeds dispersed by wind, water and animals. Vegetative spread from rhizomes. Human-mediated dispersal through dumping of garden waste, deliberate plantings and movement of contaminated soil, machinery and produce.

Impact on environment

Can displace native vegetation. Toxic to livestock.


Site Management

Follow up treated areas 3 times per year. Encourage natural regeneration of native plants or replant treated areas where possible after 2-3 treatments to establish dense ground cover and minimise reinvasion.

Recommended approaches

Physical control

Method: Dig or pull out.

Plant parts requiring disposal: All parts.

Disposal options: Remove to greenwaste or landfill


Check for the presence of agents: St John's wort beetles (Chrysolina hyperici and Chrysolina quadrigemina).

For more information about how biocontrol works, see What is biocontrol?

Community agrichemical control recommendations

Basic Growsafe certified: Foliar spray with 200ml glyphosate green per 10L of water.

Certified Handler/Experienced agrichemical user: Foliar spray with 200ml glyphosate green per 10L of water and 20ml penetrant.

Caution: When using any herbicide or pesticide please read the label thoroughly to ensure that all instructions and safety requirements are followed.

Close up of St John's wort flowers.
St John's wort has branching stems and bright yellow flowers with black dots lining the edges.
St John's Wort flowers.
Sometimes leaves also have a series of translucent black dots on their surface.
Photo credit: Greg Hoskins